I am on the team Ibelin having the hots for Latte. At the start we saw a lot of the "?" From Ibelin and rather often she seemed genuinely absent minded.
Plus, even if the settings are similar, some parts of the story are clearly different, like how the position of the moon was different from how it was in the story when Ibelin was singing.
Also, early on Ibelin was very pushy with one of the Male leads to retrieve Lotte away from the orcs, something I don't think a conniving person would do. And she usually only gets angry when it has something to do with Lotte being mistreated.
In short, I think her being jealous of Lotte is a red herring (kinda). Honestly I actually think she might be bit of a yandere for Lotte. That or slightly obsessed with her. ^_^,